Recently, an ionomer resin has widely been used as a base resin for a cover of golf balls (e.g. Japanese Laid-Open Patent Publication No. 49-27093). Particularly, the ionomer resin is exclusively used in a two-piece golf ball containing a solid core. This is because the ionomer resin is superior in rebound performance, cut resistance, etc. as well as processability.
However, a golf ball using the ionomer resin as the base resin of the cover is inferior in shot feel and controllability (ease of putting spin on the ball) in comparison with a thread wound golf ball using a balata (transpolyisoprene) as the base resin for the cover because the ionomer resin has high hardness and rigidity.
Therefore, various trials of softening the ionomer resin due to various means to improve shot feel and controllability have been made. However, there was a problem that rebound and flight performances are deteriorated by the softening and satisfactory results have not been obtained.
As described above, the golf ball using the ionomer resin as the base resin of the cover is inferior in shot feel and controllability. In addition, the attempts at improvements have not succeeded because of deterioration of rebound and flight properties.